Human stem cells are totipotential or pluripotential precursor cells capable of generating a variety of mature human cell lineages. Evidence exists that demonstrates that stem cells can be employed to repopulate many, if not all, tissues and restore physiologic and anatomic functionality.
Many different types of mammalian stem cells have been characterized. See, e.g., Caplan et al., U.S. Pat. No. 5,486,359 (human mesenchymal stem cells); Boyse et al., U.S. Pat. No. 5,004,681 (fetal and neonatal hematopoietic stem and progenitor cells); Boyse et al., U.S. Pat. No. 5,192,553 (same); Beltrami et al., Cell 114(6):763-766 (2003) (cardiac stem cells); Forbes et al., J. Pathol. 197(4):510-518 (2002) (hepatic stem cells). Umbilical cord blood, and total nucleated cells derived from cord blood, have been used in transplants to restore, partially or fully, hematopoietic function in patients who have undergone ablative therapy.